1. Field of the Invention
The present invention relates generally to a differential detection technique for MPSK (multiple-phase shift keying), and more specifically to a method of implementing differential detection for MPSK using multiple-symbol observation interval. The instant invention is highly suited for use in a digital mobile communications system wherein signal transmission paths are susceptible to multipath phasing or the like.
2. Description of the Related Art
It is known in the art that in applications where signal transmission tends to be deteriorated due to multipath fading, differential detection is preferably used rather than coherent detection. One approach to reduce the incidence of error inherent in differential detection is to use multiple symbols. One example of such techniques is disclosed in a paper entitled "Multiple-Symbol Differential Detection of MPSK" by D. Divsalar, et al., IFFE Transactions on Communications, Vol. 38, March 1990.
According to this technique art, a plurality of symbols are simultaneously detected using differential detection techniques. That is, the related art says that increasing the number of symbols simultaneously demodulated provides improved detection characteristics.
However, the prior art has suffered from the problem that the amount of calculation becomes extremely large and the hardware needed to perform this process becomes extremely bulky.